1. Field of the Invention
The present invention relates generally to valves, and more particularly, but not by way of limitation, to an improved gate valve for controlling the flow of fluids from a well during wild well blowouts. The present invention relates further to devices for shearing/severing any and all drilling tools inside a drilling blowout preventer (BOP), or likewise all the pipe or tubing inside the largest casing size during the production phase for land and subsea service. The present invention therefore relates to an improved gate valve for controlling the flow of drilling fluids and hydrocarbon fluids and gases in a state of free flow known as blowout in drilling and production phases, in combination with a shearing device for clearing the blowout flow path of obstructions that would otherwise prevent the closure of the gate valve.
2. Description of the Related Art
The control and containment of free flowing drilling fluids, hydrocarbon fluids and gases is critical. To this end the present day blowout preventers (BOPS) have a long history of failure. In particular the shear rams commonly used today are hydraulic operated and are typically only designed to cut the tube section of the drill pipe being used. In addition, shear rams rely for proper placement and function on the drill pipe being in a center position of the hole to cut or sever the drill pipe tube only. Most blowouts, however, occur during the tripping phase of drilling and as a result, other drilling tools such as drill collars and/or down hole tools are frequently within the section to be closed. A second significant cause for failure of blowout preventers used today results from the fact that typically only the body of the BOP is tested at API recommended pressures. The internal components of BOPs used today rely on elastomeric components installed in grooves to make contact with the body. These elastomeric components will generally not contain higher pressures above 5,000 PSI. Therefore, the BOPs in use today are significantly overrated for higher pressures.
Likewise, the blind rams typically used in BOPs currently are manufactured in the same manner using elastomeric components installed in grooves to make contact with the inside of the BOP bodies to provide a sure seal, but as with shear rams, the elastomeric components will only retard and contain pressures up to 5,000 PSI. The entire stack of most BOPs in use today is therefore typically overstated (and thus overrated) in the pressures they will contain.
Other deteriorating effects can cause BOP failure. For example because of the abrasive and often times corrosive nature of drilling fluids and methods used in drilling today the BOP bodies do not retard those things from invading between the BOP body and blowout preventer parts installed. Therefore each time the preventer is moved from one well being drilled to another a full tear down must ensue. The cost of doing is monumental and takes a great deal of time, thus resulting in down time for the rig where the BOP was assigned to work.
All the problems discussed above, as well as others, increase operating costs and increase the chance of injury due to equipment failure. Thus, a need has long existed for an improved gate valve and shearing assembly. Therefore the improved gate valve presented in essence acts in place of, or as a supplement to the blind rams used today. The improved design features hard sealing surfaces resistant to galling and scratching and which is designed to prevent the invasion of drilling fluids free flowing gases and fluids into the valve body therefore the valve lubricant stays in place for multiple use without expensive tear downs after each well all the while being inexpensive to manufacture, easy to maintain and convenient to operate.
Recent offshore production blowout events have peaked interest in how to bring about a cure when commodity blowout preventers fail. Therefore the present improvements are directed to the gate valve field. The improved gate valve can be used to stop an entire blowout pressure flow, and hold back that flow until other measures may be used to kill the well and/or cement the formation. A further obstacle to a failsafe system however, is how to cut and demolish all objects in the flow path that the gate would have to pass through to stop the flow.
The second critical component of a failsafe solution is therefore a system for directing an implosion of the steel parts inside in the through-bore being drilled. This implosion would allow the gate to pass from open to close. A critical issue in this regard relates to the actual placement of the shearing components with respect to the operable gate valve. The preferred placement of the shearing assembly is on top of the gate valve. In this manner of placement, at the time of implosion, the top pipes would snap back up toward the rig and the bottom pipes would fall down into the hole due to gravity. This process results in creating a clean path for the gate to pass from open to close.
Another important feature of the present invention relates to the events following the gate valve closure that would allow recovery of the well. The solution was to install a high-pressure fail-safe check valve in the center of the gate during the manufacturing process. Thereby when normal drilling activities were restored mud and other agents could be pumped down the hole through the check valve to regain control. Once the pressures were equalized the valve could be opened again allowing full openings to the hole for work to re-commence.
The design of the gate valve of the present invention may be generally seen as a modification of the gate valve structure disclosed in U.S. Pat. No. 5,377,955, issued in the name of the present Applicant/Inventor, the full disclosure of which is incorporated by reference. The gate valve design has internals that are unique that provides added protective provisions to restrict flowing fluids and gases from entering the valve body while in the open position.
In general drilling activities involves the injection of drilling fluids to aid the bit in penetration of the solids, and then the drilling fluids carry back the drill bit cuttings. Therefore when the valve is full open none of those returning solids will penetrate inside the gate valve body. Hence the lifetime of the gate valve is enhanced.
During times of well blowout the fluids and gases will pass through the open position of the gate valve. During blowout larger and harsher debris may be free flowing, also the pressures may be greatly increased because stable drilling pressures have been compromised. Therefore the valve body by not being filled with flow through fluids will operate freely from open to close in an instant.
During blowout the instant the hydraulic valve closes. Shock waves caused by the sudden stop of fluids and gases have little to no effect on the valves internals. Also the encroachments of solids and gases inside the valve body have been reduced by the design of the internal valve parts, metals used metallurgy applied and assembly techniques. Thus the valve stellar design engineering and manufacturing processes has proven to be the far improved and more reliable control of free flowing fluids and gases during blowout and for the sub sea ultimate containment of such while work resumes to again gain control.
The fail safe blowout container of the present invention is designed to repeat its work over again after blowout without being removed brought back to surface for repair or upgrade. Thus this giant leap forward using the Fail Safe Blowout container will move sub sea oil and gas exploration drilling completion and production into a much safer arena for all concerned. While at the same time bring about a more sane control of the capital set back to cure wild well blowouts. While at this time has many good solid oil and gas entities held in a quagmire of financial jeopardy because of the risk involved using present day blowout prevention prior Art.
Held inside the shear/destroy spool are the shot rings; the number of those needed for each separate well design are at the option of the oil and gas producer. Thus again providing the needed control of the total drilling completion and production of sub sea oil and gas in the control of each producer and to which government agencies and countries that are in control of those assets.
The blowout containment system becomes the one product in the production of subsea oil and gas that must be prepared for use using the most recent technological advances in engineering, manufacturing techniques metals used, metallurgy and assembly techniques.